1. Field of the Invention
The present invention relates in general to electrochromic materials for use in electrochromic devices, and more particularly, to anodic electrochromic materials comprising substituted metallocenes.
2. Background Art
Electrochromic materials have been known in the art for several years. Furthermore, experimentation associated with the utilization of metallocenes and simple substituted metallocenes as anodic electrochromic materials has also been explored. While the utilization of such anodic electrochromic materials in electrochromic devices has been identified, they have not exhibited sufficient thermal and/or ultraviolet stability characteristics for long term use in electrochromic devices.
It is therefore an object of the present invention to provide an anodic electrochromic material comprising a substituted metallocene having constituents which substantially protect the metal center from chemical reactions that would otherwise adversely affect stability of the same.
These and other objects of the present invention will become apparent in light of the present specification, claims, and drawings.
The present invention is directed to an electrochromic device comprising: (a) at least one substantially transparent substrate having an electrically conductive material associated therewith; and (b) an electrochromic medium which comprises: (1) a solvent; (2) a cathodic material; and (3) an anodic electrochromic material represented by the formula: 
wherein M comprises a transition metal; wherein X1-X10 are the same or different and comprise C, Si, or H; wherein Rn1-Rn10 are the same or different and comprise O, C, or a straight or branched alkyl, aryl, alkaryl, or aralkyl group containing approximately 1 to approximately 40 carbon atom(s), wherein the carbon atom(s) may be a linking group to, or part of, one or more functional groups comprising nitrites; nitro constituents; sulfoxides; sulfonates; phosphonium constituents; phosphonates; phosphonites; ammonium constituents; viologens, including bipyridinyl constituents; carbonyls, including carbonates, carbamates; ketones; esters; and amides; ethers, including polyethers; amines, including tertiary amines; alkenes; alkynes; and mixtures thereof; wherein n1-n10 are the same or different and comprise 0, 1, 2, or 3, and are the number of bonds between a given X and associated constituent(s) other than hydrogen; wherein Z1-Z10 are the same or different and comprise 0 or 1; and wherein                     ∑                  y          =          1                10            ⁢              n        y              ≥    7    ;                    ∑                  y          =          1                10            ⁢              z        y              ≥    7    ;            or      ⁢              xe2x80x83            ⁢                        ∑                      y            =            1                    10                ⁢                  (                                    n              y                        +                          z              y                                )                      ≥    9.  
The present invention is also directed to an electrochromic device comprising: (a) at least one substantially transparent substrate having an electrically conductive material associated therewith; and (b) an electrochromic medium which comprises: (1) a solvent; (2) a cathodic material; and (3) an anodic electrochromic material represented by the formula: 
wherein R1-R10 are the same or different and at least three of R1-R10 are the same or different and comprise a straight or branched alkyl, aryl, alkaryl, or aralkyl group containing approximately 1 to approximately 40 carbon atom(s), and/or a silyl or siloxyl group containing approximately 1 to approximately 40 silicon atom(s), wherein the carbon or silicon atom(s) may be a linking group to, or part of, one or more functional groups comprising nitrites; nitro constituents; sulfoxides; sulfonates; phosphonium constituents; phosphonates; phosphonites; ammonium constituents; viologens, including bipyridinyl constituents; carbonyls, including carbonates, carbamates; ketones; esters; and amides; ethers, including polyethers; amines, including tertiary amines; alkenes; alkynes; and mixtures thereof; wherein any remainder of R1-R10 comprise H; and wherein M comprises a transition metal.
Preferably some or all of constituents R1-R10 serve to increase stability of the metallocene relative to the stability of the metallocene without the constituents.
The present invention is also directed to an electrochromic medium comprising one or more solvents, one or more cathodic materials, and one or more above-identified anodic electrochromic materials.
The present invention is further directed to an electrochromic device comprising at least one substantially transparent substrate having an electrically conductive material associated therewith, and an above-identified electrochromic medium.